Post-Tropical Cyclone Leslie Forecast Discussion (Text)

000
WTNT43 KNHC 132036
TCDAT3
Post-Tropical Cyclone Leslie Discussion Number 70
NWS National Hurricane Center Miami FL AL132018
500 PM AST Sat Oct 13 2018
After a total of 70 advisories, long-lived Leslie has become
post-tropical just west of the coast of Portugal, finally succumbing
to the combination of cool waters, strong vertical wind shear, and
interaction with an approaching cold front. The air mass ahead of
the cyclone has moistened up in the low levels with Faro, Portugal,
reporting a dewpoint of 70F/21C, but the dewpoints across central
and northern Portugal ahead of Leslie are only in the low-60F range,
which is not indicative of a tropical air mass. Thus, the cyclone is
now a powerful post-tropical low pressure system that even has a
partial eye noted in the most recent 2000Z Portuguese composite
radar imagery. After landfall, rapid weakening is anticipated, and
Leslie is forecast to degenerate into a broad low pressure area over
or just north of Spain by late Sunday.
Leslie is moving quickly toward the northeast or 050/30 kt.
Post-tropical Cyclone Leslie should continue in a fast northeastward
direction for the next 12-18 hours, making landfall near or just
south of Porto, Portugal by 14/0000Z. This forecast motion is
consistent with the previous advisory and the latest track model
guidance.
The meteorological services of Portugal and Spain are handling
hazards information for their respective countries via local weather
products. This is the last National Hurricane Center (NHC) advisory
on this system.
Key Messages:
1. Leslie is expected to bring near hurricane-force winds to
portions of Portugal later tonight as a powerful post-tropical
cyclone. Gale-force winds are also likely to affect portions of
northwestern and northern Spain tonight and Sunday.
2. Leslie is expected to produce rainfall amounts of 25 to 75 mm (1
to 3 inches) with isolated amounts as high as 125 mm (5 inches)
across portions of Portugal and Spain, which could cause flash
flooding.
3. For more information on Leslie, interests in Portugal should
refer to products from the Portuguese Institute for Sea and
Atmosphere at www.ipma.pt. Interests in Spain should refer to
products from the State Meteorological Agency at www.aemet.es.
FORECAST POSITIONS AND MAX WINDS
INIT 13/2100Z 40.5N 9.5W 60 KT 70 MPH...POST-TROPICAL
12H 14/0600Z 43.0N 4.9W 35 KT 40 MPH...POST-TROPICAL INLAND
24H 14/1800Z...DISSIPATED
$$
Forecaster Stewart